I have heard Rudd's Carbon Pollution Reduction Scheme (CPRS) referred to as a carbon tax with an elaborate tax evasion scheme attached. Basically, it is a tax because the price of emissions is capped. If the target is exceeded, you can just buy the permits from the government. I think it is taxed at $20 per ton, which works out to about 5c per litre for petrol - hardly enough to force people into making significant cuts, though it may have more impact on electricity. The trading scheme only comes into play as a way to pay less than the tax, (or capped price) but given that the cap is so low the traded price is likely to reach the cap anyway.